Micro open-cup flash tester



June 7, 1960 w. P. cRoPPi-:R ETAL 2,939,313

MICRO OPEN-CUP FLASH TESTER Filed Oct. 7, 1957 2 Sheets-Sheet l ,ALI'ALlails la l 1 '...uzm We.

dwf/Vlg( June 7, 1960 w. P. CRQPPER ET AL 2,939,313

MICRO OPEN-CUP FLASH TESTER Filed Oct. '7, 1957 2 Sheets-Shea?I 22,939,313 MICRO OPEN-CUP FLASH TESTER Wendell P, Cropper, Lansing,and-Frank E. De Boer, Oak Park,` lll., assignors to Standard OilCompany, Chicago, Ill., a corpdrationof Indiana c Fired oet. 7, 1957,ser. No. 688,491 Y7 claims. (cl. 731-36)- This invention relates to thedetermination of the ilash point of liquids. More particularly, theinvention relates to an improved apparatus for Vrapidly and convenientlydetermining and recording the flash temperature of micro samples ofhydrocarbon liquids in routine laboratory analyses.

In the production of certain Vcommercial hydrocarbon products, it isdesirable to maintain a llash point within specified limits inaccordance with a prescribed specification. Heretofore the ash point hasbeen measured by one of the American Standard methods including theflagClosed Cup, YPensky-Martens Closed Cup, and the Cleveland Open Cup., Ineach of these methods, a sample of substantial size is heated at aprescribed rate and a test ame of precise size is inserted periodicallyinto the space above the heated sample. The liquid temperature at whichthe vapor in such space from the sample ashes is designated as the FlashPoint of the hydrocarbon liquid under test.

'I'he Cleveland Open Cup 'test is used to determine the ash points ofpetroleum products in the range of 200 F. to 600 F. The test takes aconsiderable time because of the large sample 4size (50 to 70 ml). Eventhe quickest ash point test requires substantially longer thanminutesper sample and when maximum accuracy is desired, the test takeseven longer land about minutes may be necessary. In view of the longtime necessary to make the test, the large volume of sample needed, andthe great care required for conducting the conventional test indetermining the ash point, it had not heretofore been convenient tohandle a large number of samples in the routine flash point analyses.Further, where only small amounts of sample are available, as may be thecase in fuel research and development work, no vsystem is available forrapidly andconveniently Vdetermining ash point.

In a large petroleum laboratory, 6,000 to 10,000 ash point tests permonth may be conducted and it is apparent that there is considerableincentive to provide a rapid system, employing micro samples, and whichis adaptable for routine quality control work.

It is, therefore, a primary object of this invention to provide a methodand apparatus for determining ash point on a micro scale. It is afurther object of this invention to provide a ash point determiningsystem which has an accuracy comparable to the best of the Standardmethods. A further object of the invention is to provide a flash pointapparatus which is adapted for use in routine analyses of a large numberof samples. It is an additional object of the invention to provide sucha system which requires a substantially shorter period of time forconducting the test. A further object is to provide a reliable flashpoint instrument which does not require a precise measurement of thevolume of the sample, is of simple and rugged construction and whichdoes not require an operator having highly developed technical skills.These and other objects of the invenaent 1 bar in Figure 4 showingassociated accessories;

at'ented June 7, 196() conductive material, the bar accommodating aplurality of shallow cups in longitudinally spaced array allflg the topsurface of the bar. A thermal gradient is established along the lengthof the bar. In this Way, each cup is at different temperatures, the cuphaving the highest temperature being nearest the heater. To establishthe proper thermalr gradient, we may' varythe geometry of the bar, .theheat-reflective properties of the bar may b controlled by insulation,ns, bright surfaces or the like, or the net hcatinput-` to the bar maybeY varied vas by using spaced heaters of different capacity or a singleheater at one end of the bar and providingY cooling Y means at the otherend of the bar. If desired, two or more of these means for controllingthe net heat retention at any spaced point in the bar can be used'.

Further details and advantages of our system will be describedbyreference to an embodiment of the invention illustrated in theaccompanying drawings wherein:

Figure l is an elevation schematically general assembly of theapparatus; y L- Figure 2 is a p'la`n view of the apparatus inFigure l;Figure 3 is a section taken along `the :line`,3-,-3,in Figurel; j Figure4 is a schematic illustration of anotherembodi ment of our invention;and A. Figure 5 is an end -viewV of,thetemperatureV gradient Referringtothe drawings, the bar-10 whiclirnay be made of metal, such as brass,stainless Steel, Vtinned copper or the like, is provided with apluralityofcups 11 having a capacity of about l.5 cc. each. The bar 1,0is heated by cartridge heater 12 and is cooled'V by cooling jacket 13. Asuitable thermostat 14 can lcontrol. the

relative rates' of heating by 12 and`cooling` by '13 so temperature,thehottest cup 11 being'nearest the Uheater 12 and the coolest beingnearest the jacket l13. Although we prefer to retain the `sample'directly lin the4- cups 11 in the bar \10,.we may provide cup inserts(fno't shown) of high heat-conductivity.

The samples may be removed from the lcups 11 V'after the determinationof the flash point by one lof several means. The sample may be withdrawnby suction, it may be discharged by rotating the bar v10 about Vitslongitudinal axis, or we may provide drain channels 15 closed at theirlower ends by the spring-loaded capY 16. By

compressing spring 17 in turning the lever, 18, the"ca p 16 iswithdrawn. A j' l A collecting trough 119 is' disposed below the bar 10and is inclined downwardly to drain 20 which discharges residual samplesinto a sump` V The temperature of the cups 11 is monitoredby meansv of aplurality of thermocouples 21 peened into thebar 10 adjacent to each cup11 and connected through approf priate electrical equipment to anindicator-recorder 2 2,

The dash point determination is made by noting the4 temperature of thethermocouple 21 located between the cup 11 that dashed and the adjacentcup thatfailed to ash. This temperature is correlated with the ClevelandOpen Cup Flash Point. If desired, a scale (not shown); calibrated inCleveland Flash Point may be aligned with the cups 11 for routine go,no-go` testing. In making a test with this equipment, several cups 11"in the vicinity of the cup in which the operator, by ex; perience hasreason to believe will be at the ash point," are filled with the liquidunder test. The samples are permitted to stand for about one minuteuntil the samples showing the anden about 0.6 25 'inch centers.

are inV thermal Y*equilibrium withY the bar V surrounding VeachV cupV"1`1'. )Between one and YtwoV minutes after the `'sample has beenintroduced into the cup,.the ignitor means 23 is moved along the b ar 19over tbeCXPosed cups `11 until a'ilash' occurs.' The ignito'r means mayj broadrangeof 100 F. to V700," F.; it permits theinspeccompi'iselagsmallgasfflame or a spark gapZfl as shown butVinfeithercase the spark or flame shouldtbevvery small. e VIfdesired,fan.array of 4ignitor means 23 can-V bev aligned with'each cup1,11 'and the spark gap energized ,selectivelyv VorQsequent-ially eithermanually or in ani automatic manner."Y

gn embodiment of the V'invention is 'illustrated by Fig-Q 'i urew4whichsimple andl well adapted'forroutine .Y

j laboratory use.v The temperaturegradientbar ,25 'ifs' of "coppenislabout onejincli in cross-section and'is .aboutfZO inches 'long'.V`VAbout oneinch from Vth e'; co oler end 25a `cups T26, f 'These clipsare essentially h emisphejricalV ,Cavities about 0.375Qinch in diameter;about 0.25finchdecp,

j 'A series offtwenty 'Iron- Constantan'thermocouples 3:27

K' isY placed 'between' the twenty-.one sample cups A2650 that e Vthe.junctinns'of the thermocouples 27 fall von a line vpartion to be madeveiyerapidly because of the short time taken to heatthe micro sample;and its precision is at least as good as' that required in the ClevelandOpen Cup test in the 350 F. to 500 F. range. Y

VvAlthough our invention has been described with refer- 4ence toparticular embodiments thereof, it should be understood that thesearebyw ay,. of.illustrationonlvV The invention is not necessarily limited tothedescbedembodiineats 'since :alternative i componeme and .operatingtechniques will become apparent .to -thosefskilledj-in'the Yart'V inView of Your foregoing Ydisclosure4"Accorilingly,

. termining said thermal gradient, and means for sllbietallel Vtowand ibove thelongitudinal axis of the 'bar' 2S'and Y atfa depth "inthe barcorresponding toi'th'e level ,of'

the bottomo'f the sample cups 26,.i.e. about-0.25 inchVfrorn"thierup'per surface of 'the bar. The ther'rnocouples 27arefconnected through a'sngle-pole VZtl-position ,switch 2 8 to abroadirang'e temperature-indicating meter 29. 7 Y The heated vend 2517of the temperature gradientA bar 2 5is provided with an. endchamber 30which anonimodates the 350 VWatfoartridge Vtype heater 3-1. Means (notshown in Figure 4) for cooling the end 25a of the' y bar"25 maybje'provided as described in connection with Fgurel. Y

'The procedure Vfor making the ash point determinationsis essentiallyasdescribed'with respect Vto Figures V11-3 inclusive. Thus the sampleisV placed within the cups 26, 'the bar 25 isY heated bymeansiof acartridge heatere3,1la sparking idevice 32 is placed above kthe cupsV VV2 6 containing the sample under test,rand when a ash 'occurs,fthetemperature Vis noted as' a measure of the The `spark ing device 32"comprises neon-tubeV trans'- former 33 havingV a 5000 volt secondaryand theelecv ..trodes 3473411 providing about a 0.125A inch spark g'ap.l Afpllshrbutton switch-'31.5 inthe primary circuit `of* the Ytransformer 33 controls f Y Y Wemayiprovidea As erie's'bf pairs ofelectrodes34f34a,

e- `sparking' across the gap.Y

one`for l,each cup 26, and connected through a multiposition switch (notshown), Howeven a useful unit is i provided byA mounting the sparkingdevice 32 ona carrier such as Y schematically shown in Figure 5 andadapted to 4assume an indeX position in alignment v with I `a se1ected,cup 26. YWhen a ash occurs the temperature ofrthecup in question isdetermined by` reading the temperature of the two adjacent thermocouples27 which bracket ,-thepar,ticular cup 2 6.

Samples are removed from cups 26 after a test by snction through atrapped laboratory vacuum line 3 6 as s'howninigur' Y Since the range ofthe vbarj25 is about 100 F; to 700 VF. `and vsince the approximatetemperature of .a given Y series .ofups 26'will`be known, only arelatively few 'ad'ja'centcups -2 6 need Vbe filled with a sample whenthe approximateash'point of the vsample is already known. Prom' the Vrough estimation of the flash point and of the temperature of a givencup, it is contemplated that alternpeaturegradientscale mayV be appliedto b ar 25 thereby visually indicating to the operator theapproximateternperature of lthe cup 26inwhich the flash occurs.

We ,ihave'fsund vthat the principles embodied in this Yiris,t!:l 1111efr 1 t `-canV b e ,used lto determine flash points in rthe ingtoignition any vapors evolved from said cups.

ft2. Theapparatusoij` claim 1 whichincludes temperature-'indicatingmeans foreach cup. i

'3. VIn a method for determining jflash point of petro- V leum productsthe steps which comprise segregating a plurality of aliquot portionsofthe samplein an aligned array, Vmaintaining temperatureYV gradientsbetween said segregated portions, exposing each o fvsaidsegregatedportionsto .ignition until the vapor Vevolved Vfrom one of saidVportions is ignited, and ascertaining the'temperature of 'the portionwhich is at the'lowcst temperature at which ignition occurs asY theflash pointof said petroleum products. A Y l .4. An apparatus useful indetermining theflashpoint of ajheated liquid comprising'an elongatedbarof highly heat-conductive material, a plurality of runiformly spacedsegregated sample c ups in said bar, drainmeans yfrom eachV of saidcups, means for heating the Vbar at oneend thereof, means for coolingthe other end of said bar,

' V means for indicating the Aresultant temperaturegradient along saidbar, andV Vignitor means mounted above 'said bar and adapted to bemaintained in Aproximityto each Y of said cups containing a portion of asample undertest.

" v5V. An apparatus for conducting ,ash point determinations in Va rapidmanner which comprisesin ,combination an elongated bar ofrheatconductivematerial, said bar having a plurality of segregated cavities, saidcavities being of relatively small volume land being vspaced equidistantfrom eachother ValongY the'topof lsaid Abar, electrical means forVheating one end o f Said bar, cooling means applied to said bar remotefrom said `heating means, means for determining the temperature of 'saidbar at spaced points therealong and vadjacent each'cavity, and ignitionmeans adapted `to b e disposed V above and adjacent each cavity, wherebyignition of vaporslfrom a sample is noted and the temperature o f thecavity containing the sample may be determined.

6. The apparatus ofpcla'im 5 wherein the means for determining thetemperature comprisesV a plurality of thermocouplesy embedded withinfthesaidA bar intermediate said segregated cavities.

7. The apparatus of claim 5 -whichincludessuction means adapted -toremove residual samples Vfrom Ysaid cavities. Y

